/* See LICENSE for license details. */
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <pwd.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/select.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <termios.h>
#include <unistd.h>
#include <wchar.h>

#include "st.h"
#include "win.h"

#if defined(__linux)
#include <pty.h>
#elif defined(__OpenBSD__) || defined(__NetBSD__) || defined(__APPLE__)
#include <util.h>
#elif defined(__FreeBSD__) || defined(__DragonFly__)
#include <libutil.h>
#endif

/* Arbitrary sizes */
#define UTF_INVALID 0xFFFD
#define UTF_SIZ 4
#define ESC_BUF_SIZ (128 * UTF_SIZ)
#define ESC_ARG_SIZ 16
#define STR_BUF_SIZ ESC_BUF_SIZ
#define STR_ARG_SIZ ESC_ARG_SIZ

/* macros */
#define IS_SET(flag) ((term.mode & (flag)) != 0)
#define ISCONTROLC0(c) (BETWEEN(c, 0, 0x1f) || (c) == 0x7f)
#define ISCONTROLC1(c) (BETWEEN(c, 0x80, 0x9f))
#define ISCONTROL(c) (ISCONTROLC0(c) || ISCONTROLC1(c))
#define ISDELIM(u) (u && wcschr(worddelimiters, u))

enum term_mode
{
  MODE_WRAP = 1 << 0,
  MODE_INSERT = 1 << 1,
  MODE_ALTSCREEN = 1 << 2,
  MODE_CRLF = 1 << 3,
  MODE_ECHO = 1 << 4,
  MODE_PRINT = 1 << 5,
  MODE_UTF8 = 1 << 6,
};

enum cursor_movement
{
  CURSOR_SAVE,
  CURSOR_LOAD
};

enum cursor_state
{
  CURSOR_DEFAULT = 0,
  CURSOR_WRAPNEXT = 1,
  CURSOR_ORIGIN = 2
};

enum charset
{
  CS_GRAPHIC0,
  CS_GRAPHIC1,
  CS_UK,
  CS_USA,
  CS_MULTI,
  CS_GER,
  CS_FIN
};

enum escape_state
{
  ESC_START = 1,
  ESC_CSI = 2,
  ESC_STR = 4, /* DCS, OSC, PM, APC */
  ESC_ALTCHARSET = 8,
  ESC_STR_END = 16, /* a final string was encountered */
  ESC_TEST = 32,    /* Enter in test mode */
  ESC_UTF8 = 64,
};

typedef struct
{
  Glyph attr; /* current char attributes */
  int x;
  int y;
  char state;
} TCursor;

typedef struct
{
  int mode;
  int type;
  int snap;
  /*
   * Selection variables:
   * nb – normalized coordinates of the beginning of the selection
   * ne – normalized coordinates of the end of the selection
   * ob – original coordinates of the beginning of the selection
   * oe – original coordinates of the end of the selection
   */
  struct
  {
    int x, y;
  } nb, ne, ob, oe;

  int alt;
} Selection;

/* Internal representation of the screen */
typedef struct
{
  int row;         /* nb row */
  int col;         /* nb col */
  Line * line;     /* screen */
  Line * alt;      /* alternate screen */
  int * dirty;     /* dirtyness of lines */
  TCursor c;       /* cursor */
  int ocx;         /* old cursor col */
  int ocy;         /* old cursor row */
  int top;         /* top    scroll limit */
  int bot;         /* bottom scroll limit */
  int mode;        /* terminal mode flags */
  int esc;         /* escape state flags */
  char trantbl[4]; /* charset table translation */
  int charset;     /* current charset */
  int icharset;    /* selected charset for sequence */
  int * tabs;
  Rune lastc; /* last printed char outside of sequence, 0 if control */
} Term;

/* CSI Escape sequence structs */
/* ESC '[' [[ [<priv>] <arg> [;]] <mode> [<mode>]] */
typedef struct
{
  char buf[ESC_BUF_SIZ]; /* raw string */
  size_t len;            /* raw string length */
  char priv;
  int arg[ESC_ARG_SIZ];
  int narg; /* nb of args */
  char mode[2];
} CSIEscape;

/* STR Escape sequence structs */
/* ESC type [[ [<priv>] <arg> [;]] <mode>] ESC '\' */
typedef struct
{
  char type;  /* ESC type ... */
  char * buf; /* allocated raw string */
  size_t siz; /* allocation size */
  size_t len; /* raw string length */
  char * args[STR_ARG_SIZ];
  int narg; /* nb of args */
} STREscape;

static void execsh(char *, char **);
static void stty(char **);
static void sigchld(int);
static void ttywriteraw(const char *, size_t);

static void csidump(void);
static void csihandle(void);
static void csiparse(void);
static void csireset(void);
static void osc_color_response(int, int, int);
static int eschandle(uchar);
static void strdump(void);
static void strhandle(void);
static void strparse(void);
static void strreset(void);

static void tprinter(char *, size_t);
static void tdumpsel(void);
static void tdumpline(int);
static void tdump(void);
static void tclearregion(int, int, int, int);
static void tcursor(int);
static void tdeletechar(int);
static void tdeleteline(int);
static void tinsertblank(int);
static void tinsertblankline(int);
static int tlinelen(int);
static void tmoveto(int, int);
static void tmoveato(int, int);
static void tnewline(int);
static void tputtab(int);
static void tputc(Rune);
static void treset(void);
static void tscrollup(int, int);
static void tscrolldown(int, int);
static void tsetattr(const int *, int);
static void tsetchar(Rune, const Glyph *, int, int);
static void tsetdirt(int, int);
static void tsetscroll(int, int);
static void tswapscreen(void);
static void tsetmode(int, int, const int *, int);
static int twrite(const char *, int, int);
static void tfulldirt(void);
static void tcontrolcode(uchar);
static void tdectest(char);
static void tdefutf8(char);
static int32_t tdefcolor(const int *, int *, int);
static void tdeftran(char);
static void tstrsequence(uchar);

static void drawregion(int, int, int, int);

static void selnormalize(void);
static void selscroll(int, int);
static void selsnap(int *, int *, int);

static size_t utf8decode(const char *, Rune *, size_t);
static Rune utf8decodebyte(char, size_t *);
static char utf8encodebyte(Rune, size_t);
static size_t utf8validate(Rune *, size_t);

static char * base64dec(const char *);
static char base64dec_getc(const char **);

static ssize_t xwrite(int, const char *, size_t);

/* Globals */
static Term term;
static Selection sel;
static CSIEscape csiescseq;
static STREscape strescseq;
static int iofd = 1;
static int cmdfd;
static pid_t pid;

static const uchar utfbyte[UTF_SIZ + 1] = { 0x80, 0, 0xC0, 0xE0, 0xF0 };
static const uchar utfmask[UTF_SIZ + 1] = { 0xC0, 0x80, 0xE0, 0xF0, 0xF8 };
static const Rune utfmin[UTF_SIZ + 1] = { 0, 0, 0x80, 0x800, 0x10000 };
static const Rune utfmax[UTF_SIZ + 1] = { 0x10FFFF, 0x7F, 0x7FF, 0xFFFF, 0x10FFFF };

ssize_t
xwrite(int fd, const char * s, size_t len)
{
  size_t aux = len;
  ssize_t r;

  while (len > 0)
    {
      r = write(fd, s, len);
      if (r < 0)
        return r;
      len -= r;
      s += r;
    }

  return aux;
}

void *
xmalloc(size_t len)
{
  void * p;

  if (!(p = malloc(len)))
    die("malloc: %s\n", strerror(errno));

  return p;
}

void *
xrealloc(void * p, size_t len)
{
  if ((p = realloc(p, len)) == NULL)
    die("realloc: %s\n", strerror(errno));

  return p;
}

char *
xstrdup(const char * s)
{
  char * p;

  if ((p = strdup(s)) == NULL)
    die("strdup: %s\n", strerror(errno));

  return p;
}

size_t
utf8decode(const char * c, Rune * u, size_t clen)
{
  size_t i, j, len, type;
  Rune udecoded;

  *u = UTF_INVALID;
  if (!clen)
    return 0;
  udecoded = utf8decodebyte(c[0], &len);
  if (!BETWEEN(len, 1, UTF_SIZ))
    return 1;
  for (i = 1, j = 1; i < clen && j < len; ++i, ++j)
    {
      udecoded = (udecoded << 6) | utf8decodebyte(c[i], &type);
      if (type != 0)
        return j;
    }
  if (j < len)
    return 0;
  *u = udecoded;
  utf8validate(u, len);

  return len;
}

Rune
utf8decodebyte(char c, size_t * i)
{
  for (*i = 0; *i < LEN(utfmask); ++(*i))
    if (((uchar)c & utfmask[*i]) == utfbyte[*i])
      return (uchar)c & ~utfmask[*i];

  return 0;
}

size_t
utf8encode(Rune u, char * c)
{
  size_t len, i;

  len = utf8validate(&u, 0);
  if (len > UTF_SIZ)
    return 0;

  for (i = len - 1; i != 0; --i)
    {
      c[i] = utf8encodebyte(u, 0);
      u >>= 6;
    }
  c[0] = utf8encodebyte(u, len);

  return len;
}

char
utf8encodebyte(Rune u, size_t i)
{
  return utfbyte[i] | (u & ~utfmask[i]);
}

size_t
utf8validate(Rune * u, size_t i)
{
  if (!BETWEEN(*u, utfmin[i], utfmax[i]) || BETWEEN(*u, 0xD800, 0xDFFF))
    *u = UTF_INVALID;
  for (i = 1; *u > utfmax[i]; ++i)
    ;

  return i;
}

char
base64dec_getc(const char ** src)
{
  while (**src && !isprint((unsigned char)**src))
    (*src)++;
  return **src ? *((*src)++) : '='; /* emulate padding if string ends */
}

char *
base64dec(const char * src)
{
  size_t in_len = strlen(src);
  char *result, *dst;
  static const char base64_digits[256] = {
    [43] = 62, 0,  0,  0,  63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 0,  0,  0,  -1, 0,
    0,         0,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9,  10, 11, 12, 13, 14, 15, 16, 17,
    18,        19, 20, 21, 22, 23, 24, 25, 0,  0,  0,  0,  0,  0,  26, 27, 28, 29, 30, 31,
    32,        33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
  };

  if (in_len % 4)
    in_len += 4 - (in_len % 4);
  result = dst = xmalloc(in_len / 4 * 3 + 1);
  while (*src)
    {
      int a = base64_digits[(unsigned char)base64dec_getc(&src)];
      int b = base64_digits[(unsigned char)base64dec_getc(&src)];
      int c = base64_digits[(unsigned char)base64dec_getc(&src)];
      int d = base64_digits[(unsigned char)base64dec_getc(&src)];

      /* invalid input. 'a' can be -1, e.g. if src is "\n" (c-str) */
      if (a == -1 || b == -1)
        break;

      *dst++ = (a << 2) | ((b & 0x30) >> 4);
      if (c == -1)
        break;
      *dst++ = ((b & 0x0f) << 4) | ((c & 0x3c) >> 2);
      if (d == -1)
        break;
      *dst++ = ((c & 0x03) << 6) | d;
    }
  *dst = '\0';
  return result;
}

void
selinit(void)
{
  sel.mode = SEL_IDLE;
  sel.snap = 0;
  sel.ob.x = -1;
}

int
tlinelen(int y)
{
  int i = term.col;

  if (term.line[y][i - 1].mode & ATTR_WRAP)
    return i;

  while (i > 0 && term.line[y][i - 1].u == ' ')
    --i;

  return i;
}

void
selstart(int col, int row, int snap)
{
  selclear();
  sel.mode = SEL_EMPTY;
  sel.type = SEL_REGULAR;
  sel.alt = IS_SET(MODE_ALTSCREEN);
  sel.snap = snap;
  sel.oe.x = sel.ob.x = col;
  sel.oe.y = sel.ob.y = row;
  selnormalize();

  if (sel.snap != 0)
    sel.mode = SEL_READY;
  tsetdirt(sel.nb.y, sel.ne.y);
}

void
selextend(int col, int row, int type, int done)
{
  int oldey, oldex, oldsby, oldsey, oldtype;

  if (sel.mode == SEL_IDLE)
    return;
  if (done && sel.mode == SEL_EMPTY)
    {
      selclear();
      return;
    }

  oldey = sel.oe.y;
  oldex = sel.oe.x;
  oldsby = sel.nb.y;
  oldsey = sel.ne.y;
  oldtype = sel.type;

  sel.oe.x = col;
  sel.oe.y = row;
  selnormalize();
  sel.type = type;

  if (oldey != sel.oe.y || oldex != sel.oe.x || oldtype != sel.type
      || sel.mode == SEL_EMPTY)
    tsetdirt(MIN(sel.nb.y, oldsby), MAX(sel.ne.y, oldsey));

  sel.mode = done ? SEL_IDLE : SEL_READY;
}

void
selnormalize(void)
{
  int i;

  if (sel.type == SEL_REGULAR && sel.ob.y != sel.oe.y)
    {
      sel.nb.x = sel.ob.y < sel.oe.y ? sel.ob.x : sel.oe.x;
      sel.ne.x = sel.ob.y < sel.oe.y ? sel.oe.x : sel.ob.x;
    }
  else
    {
      sel.nb.x = MIN(sel.ob.x, sel.oe.x);
      sel.ne.x = MAX(sel.ob.x, sel.oe.x);
    }
  sel.nb.y = MIN(sel.ob.y, sel.oe.y);
  sel.ne.y = MAX(sel.ob.y, sel.oe.y);

  selsnap(&sel.nb.x, &sel.nb.y, -1);
  selsnap(&sel.ne.x, &sel.ne.y, +1);

  /* expand selection over line breaks */
  if (sel.type == SEL_RECTANGULAR)
    return;
  i = tlinelen(sel.nb.y);
  if (i < sel.nb.x)
    sel.nb.x = i;
  if (tlinelen(sel.ne.y) <= sel.ne.x)
    sel.ne.x = term.col - 1;
}

int
selected(int x, int y)
{
  if (sel.mode == SEL_EMPTY || sel.ob.x == -1 || sel.alt != IS_SET(MODE_ALTSCREEN))
    return 0;

  if (sel.type == SEL_RECTANGULAR)
    return BETWEEN(y, sel.nb.y, sel.ne.y) && BETWEEN(x, sel.nb.x, sel.ne.x);

  return BETWEEN(y, sel.nb.y, sel.ne.y) && (y != sel.nb.y || x >= sel.nb.x)
         && (y != sel.ne.y || x <= sel.ne.x);
}

void
selsnap(int * x, int * y, int direction)
{
  int newx, newy, xt, yt;
  int delim, prevdelim;
  const Glyph *gp, *prevgp;

  switch (sel.snap)
    {
    case SNAP_WORD:
      /*
       * Snap around if the word wraps around at the end or
       * beginning of a line.
       */
      prevgp = &term.line[*y][*x];
      prevdelim = ISDELIM(prevgp->u);
      for (;;)
        {
          newx = *x + direction;
          newy = *y;
          if (!BETWEEN(newx, 0, term.col - 1))
            {
              newy += direction;
              newx = (newx + term.col) % term.col;
              if (!BETWEEN(newy, 0, term.row - 1))
                break;

              if (direction > 0)
                yt = *y, xt = *x;
              else
                yt = newy, xt = newx;
              if (!(term.line[yt][xt].mode & ATTR_WRAP))
                break;
            }

          if (newx >= tlinelen(newy))
            break;

          gp = &term.line[newy][newx];
          delim = ISDELIM(gp->u);
          if (!(gp->mode & ATTR_WDUMMY)
              && (delim != prevdelim || (delim && gp->u != prevgp->u)))
            break;

          *x = newx;
          *y = newy;
          prevgp = gp;
          prevdelim = delim;
        }
      break;
    case SNAP_LINE:
      /*
       * Snap around if the the previous line or the current one
       * has set ATTR_WRAP at its end. Then the whole next or
       * previous line will be selected.
       */
      *x = (direction < 0) ? 0 : term.col - 1;
      if (direction < 0)
        {
          for (; *y > 0; *y += direction)
            {
              if (!(term.line[*y - 1][term.col - 1].mode & ATTR_WRAP))
                {
                  break;
                }
            }
        }
      else if (direction > 0)
        {
          for (; *y < term.row - 1; *y += direction)
            {
              if (!(term.line[*y][term.col - 1].mode & ATTR_WRAP))
                {
                  break;
                }
            }
        }
      break;
    }
}

char *
getsel(void)
{
  char *str, *ptr;
  int y, bufsize, lastx, linelen;
  const Glyph *gp, *last;

  if (sel.ob.x == -1)
    return NULL;

  bufsize = (term.col + 1) * (sel.ne.y - sel.nb.y + 1) * UTF_SIZ;
  ptr = str = xmalloc(bufsize);

  /* append every set & selected glyph to the selection */
  for (y = sel.nb.y; y <= sel.ne.y; y++)
    {
      if ((linelen = tlinelen(y)) == 0)
        {
          *ptr++ = '\n';
          continue;
        }

      if (sel.type == SEL_RECTANGULAR)
        {
          gp = &term.line[y][sel.nb.x];
          lastx = sel.ne.x;
        }
      else
        {
          gp = &term.line[y][sel.nb.y == y ? sel.nb.x : 0];
          lastx = (sel.ne.y == y) ? sel.ne.x : term.col - 1;
        }
      last = &term.line[y][MIN(lastx, linelen - 1)];
      while (last >= gp && last->u == ' ')
        --last;

      for (; gp <= last; ++gp)
        {
          if (gp->mode & ATTR_WDUMMY)
            continue;

          ptr += utf8encode(gp->u, ptr);
        }

      /*
       * Copy and pasting of line endings is inconsistent
       * in the inconsistent terminal and GUI world.
       * The best solution seems like to produce '\n' when
       * something is copied from st and convert '\n' to
       * '\r', when something to be pasted is received by
       * st.
       * FIXME: Fix the computer world.
       */
      if ((y < sel.ne.y || lastx >= linelen)
          && (!(last->mode & ATTR_WRAP) || sel.type == SEL_RECTANGULAR))
        *ptr++ = '\n';
    }
  *ptr = 0;
  return str;
}

void
selclear(void)
{
  if (sel.ob.x == -1)
    return;
  sel.mode = SEL_IDLE;
  sel.ob.x = -1;
  tsetdirt(sel.nb.y, sel.ne.y);
}

void
die(const char * errstr, ...)
{
  va_list ap;

  va_start(ap, errstr);
  vfprintf(stderr, errstr, ap);
  va_end(ap);
  exit(1);
}

void
execsh(char * cmd, char ** args)
{
  char *sh, *prog, *arg;
  const struct passwd * pw;

  errno = 0;
  if ((pw = getpwuid(getuid())) == NULL)
    {
      if (errno)
        die("getpwuid: %s\n", strerror(errno));
      else
        die("who are you?\n");
    }

  if ((sh = getenv("SHELL")) == NULL)
    sh = (pw->pw_shell[0]) ? pw->pw_shell : cmd;

  if (args)
    {
      prog = args[0];
      arg = NULL;
    }
  else if (scroll)
    {
      prog = scroll;
      arg = utmp ? utmp : sh;
    }
  else if (utmp)
    {
      prog = utmp;
      arg = NULL;
    }
  else
    {
      prog = sh;
      arg = NULL;
    }
  DEFAULT(args, ((char *[]){ prog, arg, NULL }));

  unsetenv("COLUMNS");
  unsetenv("LINES");
  unsetenv("TERMCAP");
  setenv("LOGNAME", pw->pw_name, 1);
  setenv("USER", pw->pw_name, 1);
  setenv("SHELL", sh, 1);
  setenv("HOME", pw->pw_dir, 1);
  setenv("TERM", termname, 1);

  signal(SIGCHLD, SIG_DFL);
  signal(SIGHUP, SIG_DFL);
  signal(SIGINT, SIG_DFL);
  signal(SIGQUIT, SIG_DFL);
  signal(SIGTERM, SIG_DFL);
  signal(SIGALRM, SIG_DFL);

  execvp(prog, args);
  _exit(1);
}

void
sigchld(int a)
{
  int stat;
  pid_t p;

  if ((p = waitpid(pid, &stat, WNOHANG)) < 0)
    die("waiting for pid %hd failed: %s\n", pid, strerror(errno));

  if (pid != p)
    return;

  if (WIFEXITED(stat) && WEXITSTATUS(stat))
    die("child exited with status %d\n", WEXITSTATUS(stat));
  else if (WIFSIGNALED(stat))
    die("child terminated due to signal %d\n", WTERMSIG(stat));
  _exit(0);
}

void
stty(char ** args)
{
  char cmd[_POSIX_ARG_MAX], **p, *q, *s;
  size_t n, siz;

  if ((n = strlen(stty_args)) > sizeof(cmd) - 1)
    die("incorrect stty parameters\n");
  memcpy(cmd, stty_args, n);
  q = cmd + n;
  siz = sizeof(cmd) - n;
  for (p = args; p && (s = *p); ++p)
    {
      if ((n = strlen(s)) > siz - 1)
        die("stty parameter length too long\n");
      *q++ = ' ';
      memcpy(q, s, n);
      q += n;
      siz -= n + 1;
    }
  *q = '\0';
  if (system(cmd) != 0)
    perror("Couldn't call stty");
}

int
ttynew(const char * line, char * cmd, const char * out, char ** args)
{
  int m, s;

  if (out)
    {
      term.mode |= MODE_PRINT;
      iofd = (!strcmp(out, "-")) ? 1 : open(out, O_WRONLY | O_CREAT, 0666);
      if (iofd < 0)
        {
          fprintf(stderr, "Error opening %s:%s\n", out, strerror(errno));
        }
    }

  if (line)
    {
      if ((cmdfd = open(line, O_RDWR)) < 0)
        die("open line '%s' failed: %s\n", line, strerror(errno));
      dup2(cmdfd, 0);
      stty(args);
      return cmdfd;
    }

  /* seems to work fine on linux, openbsd and freebsd */
  if (openpty(&m, &s, NULL, NULL, NULL) < 0)
    die("openpty failed: %s\n", strerror(errno));

  switch (pid = fork())
    {
    case -1:
      die("fork failed: %s\n", strerror(errno));
      break;
    case 0:
      close(iofd);
      close(m);
      setsid(); /* create a new process group */
      dup2(s, 0);
      dup2(s, 1);
      dup2(s, 2);
      if (ioctl(s, TIOCSCTTY, NULL) < 0)
        die("ioctl TIOCSCTTY failed: %s\n", strerror(errno));
      if (s > 2)
        close(s);
#ifdef __OpenBSD__
      if (pledge("stdio getpw proc exec", NULL) == -1)
        die("pledge\n");
#endif
      execsh(cmd, args);
      break;
    default:
#ifdef __OpenBSD__
      if (pledge("stdio rpath tty proc", NULL) == -1)
        die("pledge\n");
#endif
      close(s);
      cmdfd = m;
      signal(SIGCHLD, sigchld);
      break;
    }
  return cmdfd;
}

size_t
ttyread(void)
{
  static char buf[BUFSIZ];
  static int buflen = 0;
  int ret, written;

  /* append read bytes to unprocessed bytes */
  ret = read(cmdfd, buf + buflen, LEN(buf) - buflen);

  switch (ret)
    {
    case 0:
      exit(0);
    case -1:
      die("couldn't read from shell: %s\n", strerror(errno));
    default:
      buflen += ret;
      written = twrite(buf, buflen, 0);
      buflen -= written;
      /* keep any incomplete UTF-8 byte sequence for the next call */
      if (buflen > 0)
        memmove(buf, buf + written, buflen);
      return ret;
    }
}

void
ttywrite(const char * s, size_t n, int may_echo)
{
  const char * next;

  if (may_echo && IS_SET(MODE_ECHO))
    twrite(s, n, 1);

  if (!IS_SET(MODE_CRLF))
    {
      ttywriteraw(s, n);
      return;
    }

  /* This is similar to how the kernel handles ONLCR for ttys */
  while (n > 0)
    {
      if (*s == '\r')
        {
          next = s + 1;
          ttywriteraw("\r\n", 2);
        }
      else
        {
          next = memchr(s, '\r', n);
          DEFAULT(next, s + n);
          ttywriteraw(s, next - s);
        }
      n -= next - s;
      s = next;
    }
}

void
ttywriteraw(const char * s, size_t n)
{
  fd_set wfd, rfd;
  ssize_t r;
  size_t lim = 256;

  /*
   * Remember that we are using a pty, which might be a modem line.
   * Writing too much will clog the line. That's why we are doing this
   * dance.
   * FIXME: Migrate the world to Plan 9.
   */
  while (n > 0)
    {
      FD_ZERO(&wfd);
      FD_ZERO(&rfd);
      FD_SET(cmdfd, &wfd);
      FD_SET(cmdfd, &rfd);

      /* Check if we can write. */
      if (pselect(cmdfd + 1, &rfd, &wfd, NULL, NULL, NULL) < 0)
        {
          if (errno == EINTR)
            continue;
          die("select failed: %s\n", strerror(errno));
        }
      if (FD_ISSET(cmdfd, &wfd))
        {
          /*
           * Only write the bytes written by ttywrite() or the
           * default of 256. This seems to be a reasonable value
           * for a serial line. Bigger values might clog the I/O.
           */
          if ((r = write(cmdfd, s, (n < lim) ? n : lim)) < 0)
            goto write_error;
          if (r < n)
            {
              /*
               * We weren't able to write out everything.
               * This means the buffer is getting full
               * again. Empty it.
               */
              if (n < lim)
                lim = ttyread();
              n -= r;
              s += r;
            }
          else
            {
              /* All bytes have been written. */
              break;
            }
        }
      if (FD_ISSET(cmdfd, &rfd))
        lim = ttyread();
    }
  return;

write_error:
  die("write error on tty: %s\n", strerror(errno));
}

void
ttyresize(int tw, int th)
{
  struct winsize w;

  w.ws_row = term.row;
  w.ws_col = term.col;
  w.ws_xpixel = tw;
  w.ws_ypixel = th;
  if (ioctl(cmdfd, TIOCSWINSZ, &w) < 0)
    fprintf(stderr, "Couldn't set window size: %s\n", strerror(errno));
}

void
ttyhangup(void)
{
  /* Send SIGHUP to shell */
  kill(pid, SIGHUP);
}

int
tattrset(int attr)
{
  int i, j;

  for (i = 0; i < term.row - 1; i++)
    {
      for (j = 0; j < term.col - 1; j++)
        {
          if (term.line[i][j].mode & attr)
            return 1;
        }
    }

  return 0;
}

void
tsetdirt(int top, int bot)
{
  int i;

  LIMIT(top, 0, term.row - 1);
  LIMIT(bot, 0, term.row - 1);

  for (i = top; i <= bot; i++)
    term.dirty[i] = 1;
}

void
tsetdirtattr(int attr)
{
  int i, j;

  for (i = 0; i < term.row - 1; i++)
    {
      for (j = 0; j < term.col - 1; j++)
        {
          if (term.line[i][j].mode & attr)
            {
              tsetdirt(i, i);
              break;
            }
        }
    }
}

void
tfulldirt(void)
{
  tsetdirt(0, term.row - 1);
}

void
tcursor(int mode)
{
  static TCursor c[2];
  int alt = IS_SET(MODE_ALTSCREEN);

  if (mode == CURSOR_SAVE)
    {
      c[alt] = term.c;
    }
  else if (mode == CURSOR_LOAD)
    {
      term.c = c[alt];
      tmoveto(c[alt].x, c[alt].y);
    }
}

void
treset(void)
{
  uint i;

  term.c = (TCursor){ { .mode = ATTR_NULL, .fg = defaultfg, .bg = defaultbg },
                      .x = 0,
                      .y = 0,
                      .state = CURSOR_DEFAULT };

  memset(term.tabs, 0, term.col * sizeof(*term.tabs));
  for (i = tabspaces; i < term.col; i += tabspaces)
    term.tabs[i] = 1;
  term.top = 0;
  term.bot = term.row - 1;
  term.mode = MODE_WRAP | MODE_UTF8;
  memset(term.trantbl, CS_USA, sizeof(term.trantbl));
  term.charset = 0;

  for (i = 0; i < 2; i++)
    {
      tmoveto(0, 0);
      tcursor(CURSOR_SAVE);
      tclearregion(0, 0, term.col - 1, term.row - 1);
      tswapscreen();
    }
}

void
tnew(int col, int row)
{
  term = (Term){ .c = { .attr = { .fg = defaultfg, .bg = defaultbg } } };
  tresize(col, row);
  treset();
}

void
tswapscreen(void)
{
  Line * tmp = term.line;

  term.line = term.alt;
  term.alt = tmp;
  term.mode ^= MODE_ALTSCREEN;
  tfulldirt();
}

void
tscrolldown(int orig, int n)
{
  int i;
  Line temp;

  LIMIT(n, 0, term.bot - orig + 1);

  tsetdirt(orig, term.bot - n);
  tclearregion(0, term.bot - n + 1, term.col - 1, term.bot);

  for (i = term.bot; i >= orig + n; i--)
    {
      temp = term.line[i];
      term.line[i] = term.line[i - n];
      term.line[i - n] = temp;
    }

  selscroll(orig, n);
}

void
tscrollup(int orig, int n)
{
  int i;
  Line temp;

  LIMIT(n, 0, term.bot - orig + 1);

  tclearregion(0, orig, term.col - 1, orig + n - 1);
  tsetdirt(orig + n, term.bot);

  for (i = orig; i <= term.bot - n; i++)
    {
      temp = term.line[i];
      term.line[i] = term.line[i + n];
      term.line[i + n] = temp;
    }

  selscroll(orig, -n);
}

void
selscroll(int orig, int n)
{
  if (sel.ob.x == -1)
    return;

  if (BETWEEN(sel.nb.y, orig, term.bot) != BETWEEN(sel.ne.y, orig, term.bot))
    {
      selclear();
    }
  else if (BETWEEN(sel.nb.y, orig, term.bot))
    {
      sel.ob.y += n;
      sel.oe.y += n;
      if (sel.ob.y < term.top || sel.ob.y > term.bot || sel.oe.y < term.top
          || sel.oe.y > term.bot)
        {
          selclear();
        }
      else
        {
          selnormalize();
        }
    }
}

void
tnewline(int first_col)
{
  int y = term.c.y;

  if (y == term.bot)
    {
      tscrollup(term.top, 1);
    }
  else
    {
      y++;
    }
  tmoveto(first_col ? 0 : term.c.x, y);
}

void
csiparse(void)
{
  char *p = csiescseq.buf, *np;
  long int v;

  csiescseq.narg = 0;
  if (*p == '?')
    {
      csiescseq.priv = 1;
      p++;
    }

  csiescseq.buf[csiescseq.len] = '\0';
  while (p < csiescseq.buf + csiescseq.len)
    {
      np = NULL;
      v = strtol(p, &np, 10);
      if (np == p)
        v = 0;
      if (v == LONG_MAX || v == LONG_MIN)
        v = -1;
      csiescseq.arg[csiescseq.narg++] = v;
      p = np;
      if (*p != ';' || csiescseq.narg == ESC_ARG_SIZ)
        break;
      p++;
    }
  csiescseq.mode[0] = *p++;
  csiescseq.mode[1] = (p < csiescseq.buf + csiescseq.len) ? *p : '\0';
}

/* for absolute user moves, when decom is set */
void
tmoveato(int x, int y)
{
  tmoveto(x, y + ((term.c.state & CURSOR_ORIGIN) ? term.top : 0));
}

void
tmoveto(int x, int y)
{
  int miny, maxy;

  if (term.c.state & CURSOR_ORIGIN)
    {
      miny = term.top;
      maxy = term.bot;
    }
  else
    {
      miny = 0;
      maxy = term.row - 1;
    }
  term.c.state &= ~CURSOR_WRAPNEXT;
  term.c.x = LIMIT(x, 0, term.col - 1);
  term.c.y = LIMIT(y, miny, maxy);
}

void
tsetchar(Rune u, const Glyph * attr, int x, int y)
{
  static const char * vt100_0[62] = {
    /* 0x41 - 0x7e */
    "↑", "↓", "→", "←", "█", "▚", "☃",      /* A - G */
    0,   0,   0,   0,   0,   0,   0,   0,   /* H - O */
    0,   0,   0,   0,   0,   0,   0,   0,   /* P - W */
    0,   0,   0,   0,   0,   0,   0,   " ", /* X - _ */
    "◆", "▒", "␉", "␌", "␍", "␊", "°", "±", /* ` - g */
    "␤", "␋", "┘", "┐", "┌", "└", "┼", "⎺", /* h - o */
    "⎻", "─", "⎼", "⎽", "├", "┤", "┴", "┬", /* p - w */
    "│", "≤", "≥", "π", "≠", "£", "·",      /* x - ~ */
  };

  /*
   * The table is proudly stolen from rxvt.
   */
  if (term.trantbl[term.charset] == CS_GRAPHIC0 && BETWEEN(u, 0x41, 0x7e)
      && vt100_0[u - 0x41])
    utf8decode(vt100_0[u - 0x41], &u, UTF_SIZ);

  if (term.line[y][x].mode & ATTR_WIDE)
    {
      if (x + 1 < term.col)
        {
          term.line[y][x + 1].u = ' ';
          term.line[y][x + 1].mode &= ~ATTR_WDUMMY;
        }
    }
  else if (term.line[y][x].mode & ATTR_WDUMMY)
    {
      term.line[y][x - 1].u = ' ';
      term.line[y][x - 1].mode &= ~ATTR_WIDE;
    }

  term.dirty[y] = 1;
  term.line[y][x] = *attr;
  term.line[y][x].u = u;
}

void
tclearregion(int x1, int y1, int x2, int y2)
{
  int x, y, temp;
  Glyph * gp;

  if (x1 > x2)
    temp = x1, x1 = x2, x2 = temp;
  if (y1 > y2)
    temp = y1, y1 = y2, y2 = temp;

  LIMIT(x1, 0, term.col - 1);
  LIMIT(x2, 0, term.col - 1);
  LIMIT(y1, 0, term.row - 1);
  LIMIT(y2, 0, term.row - 1);

  for (y = y1; y <= y2; y++)
    {
      term.dirty[y] = 1;
      for (x = x1; x <= x2; x++)
        {
          gp = &term.line[y][x];
          if (selected(x, y))
            selclear();
          gp->fg = term.c.attr.fg;
          gp->bg = term.c.attr.bg;
          gp->mode = 0;
          gp->u = ' ';
        }
    }
}

void
tdeletechar(int n)
{
  int dst, src, size;
  Glyph * line;

  LIMIT(n, 0, term.col - term.c.x);

  dst = term.c.x;
  src = term.c.x + n;
  size = term.col - src;
  line = term.line[term.c.y];

  memmove(&line[dst], &line[src], size * sizeof(Glyph));
  tclearregion(term.col - n, term.c.y, term.col - 1, term.c.y);
}

void
tinsertblank(int n)
{
  int dst, src, size;
  Glyph * line;

  LIMIT(n, 0, term.col - term.c.x);

  dst = term.c.x + n;
  src = term.c.x;
  size = term.col - dst;
  line = term.line[term.c.y];

  memmove(&line[dst], &line[src], size * sizeof(Glyph));
  tclearregion(src, term.c.y, dst - 1, term.c.y);
}

void
tinsertblankline(int n)
{
  if (BETWEEN(term.c.y, term.top, term.bot))
    tscrolldown(term.c.y, n);
}

void
tdeleteline(int n)
{
  if (BETWEEN(term.c.y, term.top, term.bot))
    tscrollup(term.c.y, n);
}

int32_t
tdefcolor(const int * attr, int * npar, int l)
{
  int32_t idx = -1;
  uint r, g, b;

  switch (attr[*npar + 1])
    {
    case 2: /* direct color in RGB space */
      if (*npar + 4 >= l)
        {
          fprintf(stderr, "erresc(38): Incorrect number of parameters (%d)\n", *npar);
          break;
        }
      r = attr[*npar + 2];
      g = attr[*npar + 3];
      b = attr[*npar + 4];
      *npar += 4;
      if (!BETWEEN(r, 0, 255) || !BETWEEN(g, 0, 255) || !BETWEEN(b, 0, 255))
        fprintf(stderr, "erresc: bad rgb color (%u,%u,%u)\n", r, g, b);
      else
        idx = TRUECOLOR(r, g, b);
      break;
    case 5: /* indexed color */
      if (*npar + 2 >= l)
        {
          fprintf(stderr, "erresc(38): Incorrect number of parameters (%d)\n", *npar);
          break;
        }
      *npar += 2;
      if (!BETWEEN(attr[*npar], 0, 255))
        fprintf(stderr, "erresc: bad fgcolor %d\n", attr[*npar]);
      else
        idx = attr[*npar];
      break;
    case 0: /* implemented defined (only foreground) */
    case 1: /* transparent */
    case 3: /* direct color in CMY space */
    case 4: /* direct color in CMYK space */
    default:
      fprintf(stderr, "erresc(38): gfx attr %d unknown\n", attr[*npar]);
      break;
    }

  return idx;
}

void
tsetattr(const int * attr, int l)
{
  int i;
  int32_t idx;

  for (i = 0; i < l; i++)
    {
      switch (attr[i])
        {
        case 0:
          term.c.attr.mode &=
            ~(ATTR_BOLD | ATTR_FAINT | ATTR_ITALIC | ATTR_UNDERLINE | ATTR_BLINK
              | ATTR_REVERSE | ATTR_INVISIBLE | ATTR_STRUCK);
          term.c.attr.fg = defaultfg;
          term.c.attr.bg = defaultbg;
          break;
        case 1:
          term.c.attr.mode |= ATTR_BOLD;
          break;
        case 2:
          term.c.attr.mode |= ATTR_FAINT;
          break;
        case 3:
          term.c.attr.mode |= ATTR_ITALIC;
          break;
        case 4:
          term.c.attr.mode |= ATTR_UNDERLINE;
          break;
        case 5: /* slow blink */
                /* FALLTHROUGH */
        case 6: /* rapid blink */
          term.c.attr.mode |= ATTR_BLINK;
          break;
        case 7:
          term.c.attr.mode |= ATTR_REVERSE;
          break;
        case 8:
          term.c.attr.mode |= ATTR_INVISIBLE;
          break;
        case 9:
          term.c.attr.mode |= ATTR_STRUCK;
          break;
        case 22:
          term.c.attr.mode &= ~(ATTR_BOLD | ATTR_FAINT);
          break;
        case 23:
          term.c.attr.mode &= ~ATTR_ITALIC;
          break;
        case 24:
          term.c.attr.mode &= ~ATTR_UNDERLINE;
          break;
        case 25:
          term.c.attr.mode &= ~ATTR_BLINK;
          break;
        case 27:
          term.c.attr.mode &= ~ATTR_REVERSE;
          break;
        case 28:
          term.c.attr.mode &= ~ATTR_INVISIBLE;
          break;
        case 29:
          term.c.attr.mode &= ~ATTR_STRUCK;
          break;
        case 38:
          if ((idx = tdefcolor(attr, &i, l)) >= 0)
            term.c.attr.fg = idx;
          break;
        case 39:
          term.c.attr.fg = defaultfg;
          break;
        case 48:
          if ((idx = tdefcolor(attr, &i, l)) >= 0)
            term.c.attr.bg = idx;
          break;
        case 49:
          term.c.attr.bg = defaultbg;
          break;
        default:
          if (BETWEEN(attr[i], 30, 37))
            {
              term.c.attr.fg = attr[i] - 30;
            }
          else if (BETWEEN(attr[i], 40, 47))
            {
              term.c.attr.bg = attr[i] - 40;
            }
          else if (BETWEEN(attr[i], 90, 97))
            {
              term.c.attr.fg = attr[i] - 90 + 8;
            }
          else if (BETWEEN(attr[i], 100, 107))
            {
              term.c.attr.bg = attr[i] - 100 + 8;
            }
          else
            {
              fprintf(stderr, "erresc(default): gfx attr %d unknown\n", attr[i]);
              csidump();
            }
          break;
        }
    }
}

void
tsetscroll(int t, int b)
{
  int temp;

  LIMIT(t, 0, term.row - 1);
  LIMIT(b, 0, term.row - 1);
  if (t > b)
    {
      temp = t;
      t = b;
      b = temp;
    }
  term.top = t;
  term.bot = b;
}

void
tsetmode(int priv, int set, const int * args, int narg)
{
  int alt;
  const int * lim;

  for (lim = args + narg; args < lim; ++args)
    {
      if (priv)
        {
          switch (*args)
            {
            case 1: /* DECCKM -- Cursor key */
              xsetmode(set, MODE_APPCURSOR);
              break;
            case 5: /* DECSCNM -- Reverse video */
              xsetmode(set, MODE_REVERSE);
              break;
            case 6: /* DECOM -- Origin */
              MODBIT(term.c.state, set, CURSOR_ORIGIN);
              tmoveato(0, 0);
              break;
            case 7: /* DECAWM -- Auto wrap */
              MODBIT(term.mode, set, MODE_WRAP);
              break;
            case 0:  /* Error (IGNORED) */
            case 2:  /* DECANM -- ANSI/VT52 (IGNORED) */
            case 3:  /* DECCOLM -- Column  (IGNORED) */
            case 4:  /* DECSCLM -- Scroll (IGNORED) */
            case 8:  /* DECARM -- Auto repeat (IGNORED) */
            case 18: /* DECPFF -- Printer feed (IGNORED) */
            case 19: /* DECPEX -- Printer extent (IGNORED) */
            case 42: /* DECNRCM -- National characters (IGNORED) */
            case 12: /* att610 -- Start blinking cursor (IGNORED) */
              break;
            case 25: /* DECTCEM -- Text Cursor Enable Mode */
              xsetmode(!set, MODE_HIDE);
              break;
            case 9: /* X10 mouse compatibility mode */
              xsetpointermotion(0);
              xsetmode(0, MODE_MOUSE);
              xsetmode(set, MODE_MOUSEX10);
              break;
            case 1000: /* 1000: report button press */
              xsetpointermotion(0);
              xsetmode(0, MODE_MOUSE);
              xsetmode(set, MODE_MOUSEBTN);
              break;
            case 1002: /* 1002: report motion on button press */
              xsetpointermotion(0);
              xsetmode(0, MODE_MOUSE);
              xsetmode(set, MODE_MOUSEMOTION);
              break;
            case 1003: /* 1003: enable all mouse motions */
              xsetpointermotion(set);
              xsetmode(0, MODE_MOUSE);
              xsetmode(set, MODE_MOUSEMANY);
              break;
            case 1004: /* 1004: send focus events to tty */
              xsetmode(set, MODE_FOCUS);
              break;
            case 1006: /* 1006: extended reporting mode */
              xsetmode(set, MODE_MOUSESGR);
              break;
            case 1034:
              xsetmode(set, MODE_8BIT);
              break;
            case 1049: /* swap screen & set/restore cursor as xterm */
              if (!allowaltscreen)
                break;
              tcursor((set) ? CURSOR_SAVE : CURSOR_LOAD);
              /* FALLTHROUGH */
            case 47: /* swap screen */
            case 1047:
              if (!allowaltscreen)
                break;
              alt = IS_SET(MODE_ALTSCREEN);
              if (alt)
                {
                  tclearregion(0, 0, term.col - 1, term.row - 1);
                }
              if (set ^ alt) /* set is always 1 or 0 */
                tswapscreen();
              if (*args != 1049)
                break;
              /* FALLTHROUGH */
            case 1048:
              tcursor((set) ? CURSOR_SAVE : CURSOR_LOAD);
              break;
            case 2004: /* 2004: bracketed paste mode */
              xsetmode(set, MODE_BRCKTPASTE);
              break;
            /* Not implemented mouse modes. See comments there. */
            case 1001: /* mouse highlight mode; can hang the
                    terminal by design when implemented. */
            case 1005: /* UTF-8 mouse mode; will confuse
                    applications not supporting UTF-8
                    and luit. */
            case 1015: /* urxvt mangled mouse mode; incompatible
                    and can be mistaken for other control
                    codes. */
              break;
            default:
              fprintf(stderr, "erresc: unknown private set/reset mode %d\n", *args);
              break;
            }
        }
      else
        {
          switch (*args)
            {
            case 0: /* Error (IGNORED) */
              break;
            case 2:
              xsetmode(set, MODE_KBDLOCK);
              break;
            case 4: /* IRM -- Insertion-replacement */
              MODBIT(term.mode, set, MODE_INSERT);
              break;
            case 12: /* SRM -- Send/Receive */
              MODBIT(term.mode, !set, MODE_ECHO);
              break;
            case 20: /* LNM -- Linefeed/new line */
              MODBIT(term.mode, set, MODE_CRLF);
              break;
            default:
              fprintf(stderr, "erresc: unknown set/reset mode %d\n", *args);
              break;
            }
        }
    }
}

void
csihandle(void)
{
  char buf[40];
  int len;

  switch (csiescseq.mode[0])
    {
    default:
    unknown:
      fprintf(stderr, "erresc: unknown csi ");
      csidump();
      /* die(""); */
      break;
    case '@': /* ICH -- Insert <n> blank char */
      DEFAULT(csiescseq.arg[0], 1);
      tinsertblank(csiescseq.arg[0]);
      break;
    case 'A': /* CUU -- Cursor <n> Up */
      DEFAULT(csiescseq.arg[0], 1);
      tmoveto(term.c.x, term.c.y - csiescseq.arg[0]);
      break;
    case 'B': /* CUD -- Cursor <n> Down */
    case 'e': /* VPR --Cursor <n> Down */
      DEFAULT(csiescseq.arg[0], 1);
      tmoveto(term.c.x, term.c.y + csiescseq.arg[0]);
      break;
    case 'i': /* MC -- Media Copy */
      switch (csiescseq.arg[0])
        {
        case 0:
          tdump();
          break;
        case 1:
          tdumpline(term.c.y);
          break;
        case 2:
          tdumpsel();
          break;
        case 4:
          term.mode &= ~MODE_PRINT;
          break;
        case 5:
          term.mode |= MODE_PRINT;
          break;
        }
      break;
    case 'c': /* DA -- Device Attributes */
      if (csiescseq.arg[0] == 0)
        ttywrite(vtiden, strlen(vtiden), 0);
      break;
    case 'b': /* REP -- if last char is printable print it <n> more times */
      DEFAULT(csiescseq.arg[0], 1);
      if (term.lastc)
        while (csiescseq.arg[0]-- > 0)
          tputc(term.lastc);
      break;
    case 'C': /* CUF -- Cursor <n> Forward */
    case 'a': /* HPR -- Cursor <n> Forward */
      DEFAULT(csiescseq.arg[0], 1);
      tmoveto(term.c.x + csiescseq.arg[0], term.c.y);
      break;
    case 'D': /* CUB -- Cursor <n> Backward */
      DEFAULT(csiescseq.arg[0], 1);
      tmoveto(term.c.x - csiescseq.arg[0], term.c.y);
      break;
    case 'E': /* CNL -- Cursor <n> Down and first col */
      DEFAULT(csiescseq.arg[0], 1);
      tmoveto(0, term.c.y + csiescseq.arg[0]);
      break;
    case 'F': /* CPL -- Cursor <n> Up and first col */
      DEFAULT(csiescseq.arg[0], 1);
      tmoveto(0, term.c.y - csiescseq.arg[0]);
      break;
    case 'g': /* TBC -- Tabulation clear */
      switch (csiescseq.arg[0])
        {
        case 0: /* clear current tab stop */
          term.tabs[term.c.x] = 0;
          break;
        case 3: /* clear all the tabs */
          memset(term.tabs, 0, term.col * sizeof(*term.tabs));
          break;
        default:
          goto unknown;
        }
      break;
    case 'G': /* CHA -- Move to <col> */
    case '`': /* HPA */
      DEFAULT(csiescseq.arg[0], 1);
      tmoveto(csiescseq.arg[0] - 1, term.c.y);
      break;
    case 'H': /* CUP -- Move to <row> <col> */
    case 'f': /* HVP */
      DEFAULT(csiescseq.arg[0], 1);
      DEFAULT(csiescseq.arg[1], 1);
      tmoveato(csiescseq.arg[1] - 1, csiescseq.arg[0] - 1);
      break;
    case 'I': /* CHT -- Cursor Forward Tabulation <n> tab stops */
      DEFAULT(csiescseq.arg[0], 1);
      tputtab(csiescseq.arg[0]);
      break;
    case 'J': /* ED -- Clear screen */
      switch (csiescseq.arg[0])
        {
        case 0: /* below */
          tclearregion(term.c.x, term.c.y, term.col - 1, term.c.y);
          if (term.c.y < term.row - 1)
            {
              tclearregion(0, term.c.y + 1, term.col - 1, term.row - 1);
            }
          break;
        case 1: /* above */
          if (term.c.y > 1)
            tclearregion(0, 0, term.col - 1, term.c.y - 1);
          tclearregion(0, term.c.y, term.c.x, term.c.y);
          break;
        case 2: /* all */
          tclearregion(0, 0, term.col - 1, term.row - 1);
          break;
        default:
          goto unknown;
        }
      break;
    case 'K': /* EL -- Clear line */
      switch (csiescseq.arg[0])
        {
        case 0: /* right */
          tclearregion(term.c.x, term.c.y, term.col - 1, term.c.y);
          break;
        case 1: /* left */
          tclearregion(0, term.c.y, term.c.x, term.c.y);
          break;
        case 2: /* all */
          tclearregion(0, term.c.y, term.col - 1, term.c.y);
          break;
        }
      break;
    case 'S': /* SU -- Scroll <n> line up */
      DEFAULT(csiescseq.arg[0], 1);
      tscrollup(term.top, csiescseq.arg[0]);
      break;
    case 'T': /* SD -- Scroll <n> line down */
      DEFAULT(csiescseq.arg[0], 1);
      tscrolldown(term.top, csiescseq.arg[0]);
      break;
    case 'L': /* IL -- Insert <n> blank lines */
      DEFAULT(csiescseq.arg[0], 1);
      tinsertblankline(csiescseq.arg[0]);
      break;
    case 'l': /* RM -- Reset Mode */
      tsetmode(csiescseq.priv, 0, csiescseq.arg, csiescseq.narg);
      break;
    case 'M': /* DL -- Delete <n> lines */
      DEFAULT(csiescseq.arg[0], 1);
      tdeleteline(csiescseq.arg[0]);
      break;
    case 'X': /* ECH -- Erase <n> char */
      DEFAULT(csiescseq.arg[0], 1);
      tclearregion(term.c.x, term.c.y, term.c.x + csiescseq.arg[0] - 1, term.c.y);
      break;
    case 'P': /* DCH -- Delete <n> char */
      DEFAULT(csiescseq.arg[0], 1);
      tdeletechar(csiescseq.arg[0]);
      break;
    case 'Z': /* CBT -- Cursor Backward Tabulation <n> tab stops */
      DEFAULT(csiescseq.arg[0], 1);
      tputtab(-csiescseq.arg[0]);
      break;
    case 'd': /* VPA -- Move to <row> */
      DEFAULT(csiescseq.arg[0], 1);
      tmoveato(term.c.x, csiescseq.arg[0] - 1);
      break;
    case 'h': /* SM -- Set terminal mode */
      tsetmode(csiescseq.priv, 1, csiescseq.arg, csiescseq.narg);
      break;
    case 'm': /* SGR -- Terminal attribute (color) */
      tsetattr(csiescseq.arg, csiescseq.narg);
      break;
    case 'n': /* DSR – Device Status Report (cursor position) */
      if (csiescseq.arg[0] == 6)
        {
          len = snprintf(buf, sizeof(buf), "\033[%i;%iR", term.c.y + 1, term.c.x + 1);
          ttywrite(buf, len, 0);
        }
      break;
    case 'r': /* DECSTBM -- Set Scrolling Region */
      if (csiescseq.priv)
        {
          goto unknown;
        }
      else
        {
          DEFAULT(csiescseq.arg[0], 1);
          DEFAULT(csiescseq.arg[1], term.row);
          tsetscroll(csiescseq.arg[0] - 1, csiescseq.arg[1] - 1);
          tmoveato(0, 0);
        }
      break;
    case 's': /* DECSC -- Save cursor position (ANSI.SYS) */
      tcursor(CURSOR_SAVE);
      break;
    case 'u': /* DECRC -- Restore cursor position (ANSI.SYS) */
      tcursor(CURSOR_LOAD);
      break;
    case ' ':
      switch (csiescseq.mode[1])
        {
        case 'q': /* DECSCUSR -- Set Cursor Style */
          if (xsetcursor(csiescseq.arg[0]))
            goto unknown;
          break;
        default:
          goto unknown;
        }
      break;
    }
}

void
csidump(void)
{
  size_t i;
  uint c;

  fprintf(stderr, "ESC[");
  for (i = 0; i < csiescseq.len; i++)
    {
      c = csiescseq.buf[i] & 0xff;
      if (isprint(c))
        {
          putc(c, stderr);
        }
      else if (c == '\n')
        {
          fprintf(stderr, "(\\n)");
        }
      else if (c == '\r')
        {
          fprintf(stderr, "(\\r)");
        }
      else if (c == 0x1b)
        {
          fprintf(stderr, "(\\e)");
        }
      else
        {
          fprintf(stderr, "(%02x)", c);
        }
    }
  putc('\n', stderr);
}

void
csireset(void)
{
  memset(&csiescseq, 0, sizeof(csiescseq));
}

void
osc_color_response(int num, int index, int is_osc4)
{
  int n;
  char buf[32];
  unsigned char r, g, b;

  if (xgetcolor(is_osc4 ? num : index, &r, &g, &b))
    {
      fprintf(stderr,
              "erresc: failed to fetch %s color %d\n",
              is_osc4 ? "osc4" : "osc",
              is_osc4 ? num : index);
      return;
    }

  n = snprintf(buf,
               sizeof buf,
               "\033]%s%d;rgb:%02x%02x/%02x%02x/%02x%02x\007",
               is_osc4 ? "4;" : "",
               num,
               r,
               r,
               g,
               g,
               b,
               b);
  if (n < 0 || n >= sizeof(buf))
    {
      fprintf(stderr,
              "error: %s while printing %s response\n",
              n < 0 ? "snprintf failed" : "truncation occurred",
              is_osc4 ? "osc4" : "osc");
    }
  else
    {
      ttywrite(buf, n, 1);
    }
}

void
strhandle(void)
{
  char *p = NULL, *dec;
  int j, narg, par;
  const struct
  {
    int idx;
    char * str;
  } osc_table[] = { { defaultfg, "foreground" },
                    { defaultbg, "background" },
                    { defaultcs, "cursor" } };

  term.esc &= ~(ESC_STR_END | ESC_STR);
  strparse();
  par = (narg = strescseq.narg) ? atoi(strescseq.args[0]) : 0;

  switch (strescseq.type)
    {
    case ']': /* OSC -- Operating System Command */
      switch (par)
        {
        case 0:
          if (narg > 1)
            {
              xsettitle(strescseq.args[1]);
              xseticontitle(strescseq.args[1]);
            }
          return;
        case 1:
          if (narg > 1)
            xseticontitle(strescseq.args[1]);
          return;
        case 2:
          if (narg > 1)
            xsettitle(strescseq.args[1]);
          return;
        case 52:
          if (narg > 2 && allowwindowops)
            {
              dec = base64dec(strescseq.args[2]);
              if (dec)
                {
                  xsetsel(dec);
                  xclipcopy();
                }
              else
                {
                  fprintf(stderr, "erresc: invalid base64\n");
                }
            }
          return;
        case 10:
        case 11:
        case 12:
          if (narg < 2)
            break;
          p = strescseq.args[1];
          if ((j = par - 10) < 0 || j >= LEN(osc_table))
            break; /* shouldn't be possible */

          if (!strcmp(p, "?"))
            {
              osc_color_response(par, osc_table[j].idx, 0);
            }
          else if (xsetcolorname(osc_table[j].idx, p))
            {
              fprintf(stderr, "erresc: invalid %s color: %s\n", osc_table[j].str, p);
            }
          else
            {
              tfulldirt();
            }
          return;
        case 4: /* color set */
          if (narg < 3)
            break;
          p = strescseq.args[2];
          /* FALLTHROUGH */
        case 104: /* color reset */
          j = (narg > 1) ? atoi(strescseq.args[1]) : -1;

          if (p && !strcmp(p, "?"))
            {
              osc_color_response(j, 0, 1);
            }
          else if (xsetcolorname(j, p))
            {
              if (par == 104 && narg <= 1)
                return; /* color reset without parameter */
              fprintf(stderr, "erresc: invalid color j=%d, p=%s\n", j, p ? p : "(null)");
            }
          else
            {
              /*
               * TODO if defaultbg color is changed, borders
               * are dirty
               */
              tfulldirt();
            }
          return;
        }
      break;
    case 'k': /* old title set compatibility */
      xsettitle(strescseq.args[0]);
      return;
    case 'P': /* DCS -- Device Control String */
    case '_': /* APC -- Application Program Command */
    case '^': /* PM -- Privacy Message */
      return;
    }

  fprintf(stderr, "erresc: unknown str ");
  strdump();
}

void
strparse(void)
{
  int c;
  char * p = strescseq.buf;

  strescseq.narg = 0;
  strescseq.buf[strescseq.len] = '\0';

  if (*p == '\0')
    return;

  while (strescseq.narg < STR_ARG_SIZ)
    {
      strescseq.args[strescseq.narg++] = p;
      while ((c = *p) != ';' && c != '\0')
        ++p;
      if (c == '\0')
        return;
      *p++ = '\0';
    }
}

void
strdump(void)
{
  size_t i;
  uint c;

  fprintf(stderr, "ESC%c", strescseq.type);
  for (i = 0; i < strescseq.len; i++)
    {
      c = strescseq.buf[i] & 0xff;
      if (c == '\0')
        {
          putc('\n', stderr);
          return;
        }
      else if (isprint(c))
        {
          putc(c, stderr);
        }
      else if (c == '\n')
        {
          fprintf(stderr, "(\\n)");
        }
      else if (c == '\r')
        {
          fprintf(stderr, "(\\r)");
        }
      else if (c == 0x1b)
        {
          fprintf(stderr, "(\\e)");
        }
      else
        {
          fprintf(stderr, "(%02x)", c);
        }
    }
  fprintf(stderr, "ESC\\\n");
}

void
strreset(void)
{
  strescseq = (STREscape){
    .buf = xrealloc(strescseq.buf, STR_BUF_SIZ),
    .siz = STR_BUF_SIZ,
  };
}

void
sendbreak(const Arg * arg)
{
  if (tcsendbreak(cmdfd, 0))
    perror("Error sending break");
}

void
tprinter(char * s, size_t len)
{
  if (iofd != -1 && xwrite(iofd, s, len) < 0)
    {
      perror("Error writing to output file");
      close(iofd);
      iofd = -1;
    }
}

void
toggleprinter(const Arg * arg)
{
  term.mode ^= MODE_PRINT;
}

void
printscreen(const Arg * arg)
{
  tdump();
}

void
printsel(const Arg * arg)
{
  tdumpsel();
}

void
tdumpsel(void)
{
  char * ptr;

  if ((ptr = getsel()))
    {
      tprinter(ptr, strlen(ptr));
      free(ptr);
    }
}

void
tdumpline(int n)
{
  char buf[UTF_SIZ];
  const Glyph *bp, *end;

  bp = &term.line[n][0];
  end = &bp[MIN(tlinelen(n), term.col) - 1];
  if (bp != end || bp->u != ' ')
    {
      for (; bp <= end; ++bp)
        tprinter(buf, utf8encode(bp->u, buf));
    }
  tprinter("\n", 1);
}

void
tdump(void)
{
  int i;

  for (i = 0; i < term.row; ++i)
    tdumpline(i);
}

void
tputtab(int n)
{
  uint x = term.c.x;

  if (n > 0)
    {
      while (x < term.col && n--)
        for (++x; x < term.col && !term.tabs[x]; ++x)
          /* nothing */;
    }
  else if (n < 0)
    {
      while (x > 0 && n++)
        for (--x; x > 0 && !term.tabs[x]; --x)
          /* nothing */;
    }
  term.c.x = LIMIT(x, 0, term.col - 1);
}

void
tdefutf8(char ascii)
{
  if (ascii == 'G')
    term.mode |= MODE_UTF8;
  else if (ascii == '@')
    term.mode &= ~MODE_UTF8;
}

void
tdeftran(char ascii)
{
  static char cs[] = "0B";
  static int vcs[] = { CS_GRAPHIC0, CS_USA };
  char * p;

  if ((p = strchr(cs, ascii)) == NULL)
    {
      fprintf(stderr, "esc unhandled charset: ESC ( %c\n", ascii);
    }
  else
    {
      term.trantbl[term.icharset] = vcs[p - cs];
    }
}

void
tdectest(char c)
{
  int x, y;

  if (c == '8')
    { /* DEC screen alignment test. */
      for (x = 0; x < term.col; ++x)
        {
          for (y = 0; y < term.row; ++y)
            tsetchar('E', &term.c.attr, x, y);
        }
    }
}

void
tstrsequence(uchar c)
{
  switch (c)
    {
    case 0x90: /* DCS -- Device Control String */
      c = 'P';
      break;
    case 0x9f: /* APC -- Application Program Command */
      c = '_';
      break;
    case 0x9e: /* PM -- Privacy Message */
      c = '^';
      break;
    case 0x9d: /* OSC -- Operating System Command */
      c = ']';
      break;
    }
  strreset();
  strescseq.type = c;
  term.esc |= ESC_STR;
}

void
tcontrolcode(uchar ascii)
{
  switch (ascii)
    {
    case '\t': /* HT */
      tputtab(1);
      return;
    case '\b': /* BS */
      tmoveto(term.c.x - 1, term.c.y);
      return;
    case '\r': /* CR */
      tmoveto(0, term.c.y);
      return;
    case '\f': /* LF */
    case '\v': /* VT */
    case '\n': /* LF */
      /* go to first col if the mode is set */
      tnewline(IS_SET(MODE_CRLF));
      return;
    case '\a': /* BEL */
      if (term.esc & ESC_STR_END)
        {
          /* backwards compatibility to xterm */
          strhandle();
        }
      else
        {
          xbell();
        }
      break;
    case '\033': /* ESC */
      csireset();
      term.esc &= ~(ESC_CSI | ESC_ALTCHARSET | ESC_TEST);
      term.esc |= ESC_START;
      return;
    case '\016': /* SO (LS1 -- Locking shift 1) */
    case '\017': /* SI (LS0 -- Locking shift 0) */
      term.charset = 1 - (ascii - '\016');
      return;
    case '\032': /* SUB */
      tsetchar('?', &term.c.attr, term.c.x, term.c.y);
      /* FALLTHROUGH */
    case '\030': /* CAN */
      csireset();
      break;
    case '\005': /* ENQ (IGNORED) */
    case '\000': /* NUL (IGNORED) */
    case '\021': /* XON (IGNORED) */
    case '\023': /* XOFF (IGNORED) */
    case 0177:   /* DEL (IGNORED) */
      return;
    case 0x80: /* TODO: PAD */
    case 0x81: /* TODO: HOP */
    case 0x82: /* TODO: BPH */
    case 0x83: /* TODO: NBH */
    case 0x84: /* TODO: IND */
      break;
    case 0x85:     /* NEL -- Next line */
      tnewline(1); /* always go to first col */
      break;
    case 0x86: /* TODO: SSA */
    case 0x87: /* TODO: ESA */
      break;
    case 0x88: /* HTS -- Horizontal tab stop */
      term.tabs[term.c.x] = 1;
      break;
    case 0x89: /* TODO: HTJ */
    case 0x8a: /* TODO: VTS */
    case 0x8b: /* TODO: PLD */
    case 0x8c: /* TODO: PLU */
    case 0x8d: /* TODO: RI */
    case 0x8e: /* TODO: SS2 */
    case 0x8f: /* TODO: SS3 */
    case 0x91: /* TODO: PU1 */
    case 0x92: /* TODO: PU2 */
    case 0x93: /* TODO: STS */
    case 0x94: /* TODO: CCH */
    case 0x95: /* TODO: MW */
    case 0x96: /* TODO: SPA */
    case 0x97: /* TODO: EPA */
    case 0x98: /* TODO: SOS */
    case 0x99: /* TODO: SGCI */
      break;
    case 0x9a: /* DECID -- Identify Terminal */
      ttywrite(vtiden, strlen(vtiden), 0);
      break;
    case 0x9b: /* TODO: CSI */
    case 0x9c: /* TODO: ST */
      break;
    case 0x90: /* DCS -- Device Control String */
    case 0x9d: /* OSC -- Operating System Command */
    case 0x9e: /* PM -- Privacy Message */
    case 0x9f: /* APC -- Application Program Command */
      tstrsequence(ascii);
      return;
    }
  /* only CAN, SUB, \a and C1 chars interrupt a sequence */
  term.esc &= ~(ESC_STR_END | ESC_STR);
}

/*
 * returns 1 when the sequence is finished and it hasn't to read
 * more characters for this sequence, otherwise 0
 */
int
eschandle(uchar ascii)
{
  switch (ascii)
    {
    case '[':
      term.esc |= ESC_CSI;
      return 0;
    case '#':
      term.esc |= ESC_TEST;
      return 0;
    case '%':
      term.esc |= ESC_UTF8;
      return 0;
    case 'P': /* DCS -- Device Control String */
    case '_': /* APC -- Application Program Command */
    case '^': /* PM -- Privacy Message */
    case ']': /* OSC -- Operating System Command */
    case 'k': /* old title set compatibility */
      tstrsequence(ascii);
      return 0;
    case 'n': /* LS2 -- Locking shift 2 */
    case 'o': /* LS3 -- Locking shift 3 */
      term.charset = 2 + (ascii - 'n');
      break;
    case '(': /* GZD4 -- set primary charset G0 */
    case ')': /* G1D4 -- set secondary charset G1 */
    case '*': /* G2D4 -- set tertiary charset G2 */
    case '+': /* G3D4 -- set quaternary charset G3 */
      term.icharset = ascii - '(';
      term.esc |= ESC_ALTCHARSET;
      return 0;
    case 'D': /* IND -- Linefeed */
      if (term.c.y == term.bot)
        {
          tscrollup(term.top, 1);
        }
      else
        {
          tmoveto(term.c.x, term.c.y + 1);
        }
      break;
    case 'E':      /* NEL -- Next line */
      tnewline(1); /* always go to first col */
      break;
    case 'H': /* HTS -- Horizontal tab stop */
      term.tabs[term.c.x] = 1;
      break;
    case 'M': /* RI -- Reverse index */
      if (term.c.y == term.top)
        {
          tscrolldown(term.top, 1);
        }
      else
        {
          tmoveto(term.c.x, term.c.y - 1);
        }
      break;
    case 'Z': /* DECID -- Identify Terminal */
      ttywrite(vtiden, strlen(vtiden), 0);
      break;
    case 'c': /* RIS -- Reset to initial state */
      treset();
      resettitle();
      xloadcols();
      break;
    case '=': /* DECPAM -- Application keypad */
      xsetmode(1, MODE_APPKEYPAD);
      break;
    case '>': /* DECPNM -- Normal keypad */
      xsetmode(0, MODE_APPKEYPAD);
      break;
    case '7': /* DECSC -- Save Cursor */
      tcursor(CURSOR_SAVE);
      break;
    case '8': /* DECRC -- Restore Cursor */
      tcursor(CURSOR_LOAD);
      break;
    case '\\': /* ST -- String Terminator */
      if (term.esc & ESC_STR_END)
        strhandle();
      break;
    default:
      fprintf(stderr,
              "erresc: unknown sequence ESC 0x%02X '%c'\n",
              (uchar)ascii,
              isprint(ascii) ? ascii : '.');
      break;
    }
  return 1;
}

void
tputc(Rune u)
{
  char c[UTF_SIZ];
  int control;
  int width, len;
  Glyph * gp;

  control = ISCONTROL(u);
  if (u < 127 || !IS_SET(MODE_UTF8))
    {
      c[0] = u;
      width = len = 1;
    }
  else
    {
      len = utf8encode(u, c);
      if (!control && (width = wcwidth(u)) == -1)
        width = 1;
    }

  if (IS_SET(MODE_PRINT))
    tprinter(c, len);

  /*
   * STR sequence must be checked before anything else
   * because it uses all following characters until it
   * receives a ESC, a SUB, a ST or any other C1 control
   * character.
   */
  if (term.esc & ESC_STR)
    {
      if (u == '\a' || u == 030 || u == 032 || u == 033 || ISCONTROLC1(u))
        {
          term.esc &= ~(ESC_START | ESC_STR);
          term.esc |= ESC_STR_END;
          goto check_control_code;
        }

      if (strescseq.len + len >= strescseq.siz)
        {
          /*
           * Here is a bug in terminals. If the user never sends
           * some code to stop the str or esc command, then st
           * will stop responding. But this is better than
           * silently failing with unknown characters. At least
           * then users will report back.
           *
           * In the case users ever get fixed, here is the code:
           */
          /*
           * term.esc = 0;
           * strhandle();
           */
          if (strescseq.siz > (SIZE_MAX - UTF_SIZ) / 2)
            return;
          strescseq.siz *= 2;
          strescseq.buf = xrealloc(strescseq.buf, strescseq.siz);
        }

      memmove(&strescseq.buf[strescseq.len], c, len);
      strescseq.len += len;
      return;
    }

check_control_code:
  /*
   * Actions of control codes must be performed as soon they arrive
   * because they can be embedded inside a control sequence, and
   * they must not cause conflicts with sequences.
   */
  if (control)
    {
      tcontrolcode(u);
      /*
       * control codes are not shown ever
       */
      if (!term.esc)
        term.lastc = 0;
      return;
    }
  else if (term.esc & ESC_START)
    {
      if (term.esc & ESC_CSI)
        {
          csiescseq.buf[csiescseq.len++] = u;
          if (BETWEEN(u, 0x40, 0x7E) || csiescseq.len >= sizeof(csiescseq.buf) - 1)
            {
              term.esc = 0;
              csiparse();
              csihandle();
            }
          return;
        }
      else if (term.esc & ESC_UTF8)
        {
          tdefutf8(u);
        }
      else if (term.esc & ESC_ALTCHARSET)
        {
          tdeftran(u);
        }
      else if (term.esc & ESC_TEST)
        {
          tdectest(u);
        }
      else
        {
          if (!eschandle(u))
            return;
          /* sequence already finished */
        }
      term.esc = 0;
      /*
       * All characters which form part of a sequence are not
       * printed
       */
      return;
    }
  if (selected(term.c.x, term.c.y))
    selclear();

  gp = &term.line[term.c.y][term.c.x];
  if (IS_SET(MODE_WRAP) && (term.c.state & CURSOR_WRAPNEXT))
    {
      gp->mode |= ATTR_WRAP;
      tnewline(1);
      gp = &term.line[term.c.y][term.c.x];
    }

  if (IS_SET(MODE_INSERT) && term.c.x + width < term.col)
    memmove(gp + width, gp, (term.col - term.c.x - width) * sizeof(Glyph));

  if (term.c.x + width > term.col)
    {
      tnewline(1);
      gp = &term.line[term.c.y][term.c.x];
    }

  tsetchar(u, &term.c.attr, term.c.x, term.c.y);
  term.lastc = u;

  if (width == 2)
    {
      gp->mode |= ATTR_WIDE;
      if (term.c.x + 1 < term.col)
        {
          if (gp[1].mode == ATTR_WIDE && term.c.x + 2 < term.col)
            {
              gp[2].u = ' ';
              gp[2].mode &= ~ATTR_WDUMMY;
            }
          gp[1].u = '\0';
          gp[1].mode = ATTR_WDUMMY;
        }
    }
  if (term.c.x + width < term.col)
    {
      tmoveto(term.c.x + width, term.c.y);
    }
  else
    {
      term.c.state |= CURSOR_WRAPNEXT;
    }
}

int
twrite(const char * buf, int buflen, int show_ctrl)
{
  int charsize;
  Rune u;
  int n;

  for (n = 0; n < buflen; n += charsize)
    {
      if (IS_SET(MODE_UTF8))
        {
          /* process a complete utf8 char */
          charsize = utf8decode(buf + n, &u, buflen - n);
          if (charsize == 0)
            break;
        }
      else
        {
          u = buf[n] & 0xFF;
          charsize = 1;
        }
      if (show_ctrl && ISCONTROL(u))
        {
          if (u & 0x80)
            {
              u &= 0x7f;
              tputc('^');
              tputc('[');
            }
          else if (u != '\n' && u != '\r' && u != '\t')
            {
              u ^= 0x40;
              tputc('^');
            }
        }
      tputc(u);
    }
  return n;
}

void
tresize(int col, int row)
{
  int i;
  int minrow = MIN(row, term.row);
  int mincol = MIN(col, term.col);
  int * bp;
  TCursor c;

  if (col < 1 || row < 1)
    {
      fprintf(stderr, "tresize: error resizing to %dx%d\n", col, row);
      return;
    }

  /*
   * slide screen to keep cursor where we expect it -
   * tscrollup would work here, but we can optimize to
   * memmove because we're freeing the earlier lines
   */
  for (i = 0; i <= term.c.y - row; i++)
    {
      free(term.line[i]);
      free(term.alt[i]);
    }
  /* ensure that both src and dst are not NULL */
  if (i > 0)
    {
      memmove(term.line, term.line + i, row * sizeof(Line));
      memmove(term.alt, term.alt + i, row * sizeof(Line));
    }
  for (i += row; i < term.row; i++)
    {
      free(term.line[i]);
      free(term.alt[i]);
    }

  /* resize to new height */
  term.line = xrealloc(term.line, row * sizeof(Line));
  term.alt = xrealloc(term.alt, row * sizeof(Line));
  term.dirty = xrealloc(term.dirty, row * sizeof(*term.dirty));
  term.tabs = xrealloc(term.tabs, col * sizeof(*term.tabs));

  /* resize each row to new width, zero-pad if needed */
  for (i = 0; i < minrow; i++)
    {
      term.line[i] = xrealloc(term.line[i], col * sizeof(Glyph));
      term.alt[i] = xrealloc(term.alt[i], col * sizeof(Glyph));
    }

  /* allocate any new rows */
  for (/* i = minrow */; i < row; i++)
    {
      term.line[i] = xmalloc(col * sizeof(Glyph));
      term.alt[i] = xmalloc(col * sizeof(Glyph));
    }
  if (col > term.col)
    {
      bp = term.tabs + term.col;

      memset(bp, 0, sizeof(*term.tabs) * (col - term.col));
      while (--bp > term.tabs && !*bp)
        /* nothing */;
      for (bp += tabspaces; bp < term.tabs + col; bp += tabspaces)
        *bp = 1;
    }
  /* update terminal size */
  term.col = col;
  term.row = row;
  /* reset scrolling region */
  tsetscroll(0, row - 1);
  /* make use of the LIMIT in tmoveto */
  tmoveto(term.c.x, term.c.y);
  /* Clearing both screens (it makes dirty all lines) */
  c = term.c;
  for (i = 0; i < 2; i++)
    {
      if (mincol < col && 0 < minrow)
        {
          tclearregion(mincol, 0, col - 1, minrow - 1);
        }
      if (0 < col && minrow < row)
        {
          tclearregion(0, minrow, col - 1, row - 1);
        }
      tswapscreen();
      tcursor(CURSOR_LOAD);
    }
  term.c = c;
}

void
resettitle(void)
{
  xsettitle(NULL);
}

void
drawregion(int x1, int y1, int x2, int y2)
{
  int y;

  for (y = y1; y < y2; y++)
    {
      if (!term.dirty[y])
        continue;

      term.dirty[y] = 0;
      xdrawline(term.line[y], x1, y, x2);
    }
}

void
draw(void)
{
  int cx = term.c.x, ocx = term.ocx, ocy = term.ocy;

  if (!xstartdraw())
    return;

  /* adjust cursor position */
  LIMIT(term.ocx, 0, term.col - 1);
  LIMIT(term.ocy, 0, term.row - 1);
  if (term.line[term.ocy][term.ocx].mode & ATTR_WDUMMY)
    term.ocx--;
  if (term.line[term.c.y][cx].mode & ATTR_WDUMMY)
    cx--;

  drawregion(0, 0, term.col, term.row);
  xdrawcursor(cx,
              term.c.y,
              term.line[term.c.y][cx],
              term.ocx,
              term.ocy,
              term.line[term.ocy][term.ocx]);
  term.ocx = cx;
  term.ocy = term.c.y;
  xfinishdraw();
  if (ocx != term.ocx || ocy != term.ocy)
    xximspot(term.ocx, term.ocy);
}

void
redraw(void)
{
  tfulldirt();
  draw();
}
